Build your own Sun Track Diorama What about the stars? The rising points of the stars don't change as much as the Sun's because they are so very far away. So the rising points of stars on the horizon were not as critical to ancient cultures. However, the rising times of stars change by 4 minutes each day, so any particular star would rise at different times during the year. For about half the time, the star would rise during the daytime and thus be blocked by the huge light of our Sun.
There was something called the "heliacal" or dawn rise of a star -- and this happened on only one day of the year.
Thus these dawn rising were extremely useful for keeping track of exact days. For an explanation and examples of heliacal or dawn risings of stars, see Show Me a Heliacal Rising. Image credits: Medicine Wheel sunset photograph by Tom Melham. The Tom Melham picture appeared in the National Geographic.
According to them, it is part of a collection "Mysteries of Mankind: Earth's Unexplained Landmarks" and the image is listed as usuable, with no permission or payment required. Just need to give credit, which is: Medicine Wheel sunset photograph by Tom Melham.
The daily or diurnal paths of the Sun during the solstices 21 December and 21 June and the equinoxes 21 March and 21 September as seen by an observer at the equator. Solid lines are daytime, dashed lines are night-time. At all seasons on the equator, the daily paths of the Sun are divided equally above and below the horizon. The same information shown in Figure 7 is presented in Figure 7a, below, in the form of a polar plot of the position of the Sun in the coordinates of the azimuth and altitude of the Sun as seen by an observer at that latitude.
Figure 8 and 8a show the apparent paths of the Sun as seen from Hawai'i, the southernmost State of the United States, 21 degrees north of the equator. The paths are all parallel to each other, but are slanting at 21 degrees to the horizon. If the particles are of uniform size, they might impart a reddish or bluish cast to the sky, or result in an odd-colored sun or moon it is this effect that accounts for the infrequent observation of "blue suns" or "blue moons" near erupting volcanoes.
Because pollution aerosols normally exist in a wide range of sizes, however, the overall scattering they produce is not strongly wavelength-dependent.
As a result, hazy daytime skies, instead of being bright blue, appear grayish or even white. Similarly, the vibrant oranges and reds of "clean" sunsets give way to pale yellows and pinks when dust and haze fill the air. Corfidi also points out that pollutants also enhance light modification at low sun angles. This causes a reduction in the total light reaching our eyes and the overall brilliance of the sunrise.
Do clouds hurt sunrise or sunset views? According to Corfidi's essay, some clouds are preferable for the best views. I think Amanda's picture above confirms that too. He writes. Clouds catch the last red-orange rays of the setting sun and the first light of the dawn like a theatre screen, and reflect this light to the ground. The best sunrises and sunsets seem to be associated with middle to high clouds rather than lower level clouds. Higher clouds receive sunlight that has not been altered by attenuation at lower levels.
If you have a satellite dish for TV service as I do, attenuation is what happens when you lose the signal during rain. That is enough for now. I woke up with no intention of writing anything today, but Amanda' picture was a bright way to start things off.
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